Aminoplast microencapsulation system

Abstract

A description is given of a process for microencapsulating hydrophobic oils with color reactants of color reaction systems dissolved therein, a cationized melamine/formaldehyde precondensate being precipitated in ultra-fine suspension from its acid aqueous solution, accompanied by vigorous stirring and by modifying the solubility conditions, said suspension is mixed under vigorous stirring with a hydrophobic oil containing the color reactants in dissolved form, the oil-in-water dispersion obtained is adjusted acid and an aqueous solution of a water-soluble, nonionic melamine/formaldehyde precondensate is added, accompanied by stirring, for forming the microcapsule envelope. For stabilizing the oil-in-water dispersion, the pH-value of the acid, aqueous solution of a cationized melamine/formaldehyde precondensate which, in the weak acid, neutral and alkaline, aqueous use range is present in insoluble, cationizable form, is raised in the absence of water-soluble, organic polymers by the addition of Bronsted bases and accompanied by vigorous stirring to such an extent that the cationizable melamine/formaldehyde precondensate is precipitated in ultra-fine suspension as a result of the modified solubility conditions. The possible elimination of the water-soluble, organic polymers is economically advantageous.

We claim: 
     
       1. An aminoplast microencapsulation system comprising: microcapsules having an envelope consisting essentially of the condensate of a water-soluble non-ionic melamine/formaldehyde precondensate,   a hydrophobic oil encapsulated within said envelope, and   a solid surfactant consisting essentially of the precipitate of a cationic melamine/formaldehyde precondensate that is water-insoluble under weak acid, neutral and alkaline conditions.